The specter of a reunited Germany is again haunting Europe, called up by the visit last week of East German Communist leader Erich Honecker to Bonn, where he has been treated with pomp, ceremony and great hospitality by Chancellor Helmut Kohl and the West German government. In Europe this is regarded as an extremely important event.

More than six years passed between the day that former West German chancellor Helmut Schmidt extended the invitation and the day that Erich Honecker, the man who built the Berlin Wall and has governed Communist Germany with an iron hand, set foot in the Federal Republic. Several times visits were scheduled only to be canceled at the behest of the Soviet Union. That alone gave the meeting a significance beyond itself. Since it could take place only with the blessing of the Soviet Union, it now obviously has that blessing. Today Mikhail Gorbachev judges that greater intra-German contact coincides with the interest of the Kremlin.

The visit is one more proof of Gorbachev's determination ''to play a role in the great European family.'' The Soviets' own ''dynamic dialogue'' with the Federal Republic got under way earlier this summer when West German President Richard von Weizsacker visited Moscow. At that time Gorbachev also stated -- with a clarity some called threatening -- his views about the limits of rapprochement between East and West Germany: ''The existence of two German states is a fact. Any other analysis would have very serious consequences.''

For Honecker and his entourage the visit means the Federal Republic has finally accepted the existence and the legitimacy of the Communist state. They do not seem to understand that Helmut Kohl and his West German colleagues do not see it that way. To them, Honecker's visit is one more step in their determined campaign to break down the barriers between East and West Germany. As Kohl said in his opening statement, ''The people of Germany know there exist two states which have to deal practically with many issues . . . but the idea of the unity of the nation is as awake as ever, and the will to keep it is still there.''

At the top of the list of ''practical issues'' with which the two Germanys must deal is the Communist state's desire for economic assistance and West Germans' desire to promote freer passage between peoples.

With credits, technology and favorable terms of trade, Bonn buys greater freedom for their fellow Germans -- to visit, to travel, to immigrate. This year a million East Germans under retirement age will be permitted to visit the West (those past retirement age already enjoy greater freedom of movement). But travel is still tightly controlled. This year Kohl hopes to buy a change in East Germany's policy of shooting to kill anyone attempting to flee over The Wall. It is not clear he will succeed.

No one -- least of all the East German government -- knows how many of its citizens might seek to leave if the penalties were less drastic. Demonstrations beside The Wall this summer were but one reminder among many that East Germans badly want greater freedom to travel.

When they travel they see for themselves what Honecker's dismal deals reflect: that the West is able to provide its citizens with greater economic well-being and more freedom. Permitting more East Germans to see for themselves is the risk that Honecker -- and Gorbachev -- run with the new policy of ''dynamic dialogue'' with Western Europe.

There is also a risk for West Europe and for the United States in the new rapprochement. Former French foreign minister Jean Francois Poncet spelled it out in a commentary in Le Figaro. Poncet believes that ''the denuclearization of Europe, to which Washington is imprudently ready to agree, will be accompanied by an eventual reduction in American forces stationed in Europe. It could lead the Federal Republic to seek in the East the guarantees of its security which the West will no longer seem able to offer.''

A neutral Germany is already the dream of West Germany's Greens and of an influential part of the SPD. It is the nightmare of the French and other Western Europeans who understand the removal of nuclear weapons will leave them far more vulnerable to the Soviets' huge advantage in conventional forces, and who understand the importance of a strong West Germany to the defense of Western Europe.

A neutral West Germany is not yet a probability in Poncet's view, but he and others think it "sufficiently plausible to stimulate France and West Germany to construct together a new European foundation of which the Atlantic Alliance has clearer and clearer need.'' Helmut Kohl has already spoken in favor of just such a Franco-German collaboration in building a European defense of Western Europe.

One hopes the United States government will have the realism and foresight to encourage development of a European defense capacity that will enable the prosperous and competent Western European states to defend themselves while they wait for Eastern Europeans to see for themselves the benefits of freedom.